This invention relates to methods and devices used in intravascular therapeutic and diagnostic procedures and in particular to methods and devices to facilitate a guide wire exchange in conjunction with another device used for intravascular therapies and diagnostics.
Intravascular therapeutic techniques, such as angioplasty, atherectomy, and laser irradiation, have been developed as alternatives to surgery for treating vascular disease or other conditions that occlude or reduce the lumen size of portions of a patient's vascular system. Also, intravascular diagnostic techniques, such as ultrasonic imaging, and Doppler blood flow measurements, have been developed to measure or image the extent of an occlusion of a vessel, (e.g., stenosis). These intravascular diagnostic techniques may be used in conjunction with the aforementioned therapeutic techniques or may be used in conjunction with more invasive techniques such as coronary surgery.
These intravascular therapeutic and diagnostic techniques have achieved acceptance because of their effectiveness as well as the fact that they can be performed through a minor surgical procedure that is relatively non-disruptive to the patient compared to coronary surgery. The intravascular therapeutic and diagnostic procedures, mentioned above, rely on the positioning of a device into the vascular system of a patient via an incision at an accessible location which may be remote from the site of the occlusion or stenosis. The accessible location may be for example the femoral artery. The intravascular device is then advanced through the incision via one or more vessels to the desired distal site. The vessels in the distal sites into which the device may be advanced include the coronary arteries, branch vessels stemming from the external carotid artery such as the occipital and the arteries leading to the vessels of the head and brain, splenic, and the inferior mesenteric and renal arteries leading to the organs of the thorax as well as other vessels. Because of the small size of some of these vessels and the tortuous passages through the vessels, positioning of a device through a patient's vasculature can be a difficult and time consuming task requiring considerable skill on the part of the physician.
Several different approaches have been developed for positioning intravascular therapeutic or diagnostic devices such as those mentioned above through a patient's vasculature. In one approach, a guide wire tip is fixed on a distal end of the intravascular device to facilitate maneuvering the device to the desired distally remote vessel site. Another approach uses an over-the-wire construction in which a central lumen of the intravascular device can accommodate a guide wire that is movable in relation to the device to facilitate positioning the device in a remote vessel location over the guide wire. In the over-the-wire construction, the intravascular device includes a lumen adapted to receive the guide wire from a proximal end to the distal end of the device. A guide wire would initially be loaded through the over-the-wire device from the proximal end thereof. Then, the guide wire and the intravascular device are positioned in the vessel to the desired site. The guide wire may be advanced distally of the distal end of the device, as necessary, to traverse tortuous passages of the vessel. The guide wire may then be withdrawn proximally through the lumen of the device or may be left in place extending from the distal end of the device during the procedure.
With both fixed wire and the over-the-wire devices, an introducer sheath and/or a guiding catheter may also be employed. An introducer sheath is used to provide translumenal access to the femoral artery or another appropriate location. Then, with the access provided by the introducer sheath, a guiding catheter may be positioned in the patient's vessel. The guiding catheter may be advanced at least part of the way to the desired site, such as to the aortic arch. The guiding catheter has an internal lumen through which the intravascular device, including the guide wire in an over-the-wire construction, is advanced. One of the functions of the guiding catheter is to support the device. The guiding catheter may be approximately 100 to 106 cm in length. Alternatively, in certain situation, e.g. if positioning of the device does not involve traversing tortuous vessel passages, a guiding catheter may be employed to position an intravascular device without the use of a guide wire.
Intravascular therapeutic and diagnostic devices, such as angioplasty and atherectomy devices, come in various types and sizes suitable for the vessel size and location in which the treatment is to be performed. Sometimes, it becomes necessary to exchange a first therapeutic device for one of a different size after the first device has been positioned or after an unsuccessful attempt to position the first device. This may be necessitated because it becomes apparent that the first device is the wrong size or because it is determined that additional therapeutic or diagnostic procedures with a different size or type of device is required.
When it is required to exchange one device for another, it a disadvantage of a fixed wire device that it is necessary to remove the entire device and position another device to the desired site. As mentioned above, this can be sometimes a tedious and difficult procedure.
In order to exchange an intravascular device with an over-the-wire construction, it may also be necessary to remove both the device and the guide wire. This is because it is preferred not to lose a hold on the proximal end of the guide wire as the device is withdrawn over the proximal end of the guide wire. Then, in order to position a second over-the-wire device, a guide wire must again be positioned to the desired location all over again in a new procedure just as was done for the first device. This can be timeconsuming and thus requires the physician to perform again the sometimes difficult and tedious task of positioning the guide wire to the desired location. Replacement of both the device and the guide wire may also be necessary when the second device is to be advanced to a different vessel site requiring a guide wire of a different size or of different dimensions.
It is possible in some situations to exchange the intravascular device and leave the guide wire in place. This can greatly facilitate exchanging the device because the difficult task of positioning the guide wire need not be performed again. An intravascular device with an over-the-wire construction can be exchanged while leaving the distal tip of the guide wire in place according to several different methods. For example, one method is to use a guide wire having a long length (e.g. 300 cm) so that a sufficiently long proximal portion of the guide wire extends out of the proximal end of the guiding catheter in order that the entire intravascular device can be withdrawn out completely over the guide wire while maintaining a hold on a proximal portion of the guide wire. This method has the disadvantage that the long proximally extending portion of the long guide wire may be in the way during the procedure. Another method to exchange an intravascular device with an over-the-wire construction is by using a guide wire extension. A description of this method is in "Guide Wire Extension", by C. Cope, M.D., Radiology 1985; 157:263 (1985). A disadvantage of this method is that not all guide wires are adapted to connect to an extension wire, and moreover, the step of connecting the guide wire to the extension wire can sometimes be tedious and difficult to do.
One approach that is employed to facilitate exchange of intravascular devices is the "single-operator-exchange" construction. With the single-operator-exchange construction, a guide wire occupies a position adjacent to the intravascular device along proximal and middle portions of the device and enters into a lumen of the device via a laterally-oriented opening at a location close to a distal portion of the device. With this construction, the device can be positioned in the patient's vessel by positioning a guide wire in the desired location and advancing the device over the wire. However, in the event that it becomes necessary to exchange the single-operator-exchange device, the device can be withdrawn proximally while the distal tip of the guide wire is left in position in the vessel site. Because the proximal end of the guide wire and the proximal end of the device are adjacent to each other, the proximal end of the guide wire can be secured so that the position of the distal end of the guide wire in the patient's vessel can be maintained. With this type of device, it is necessary that the distance from the distal end of the device to the lateral proximal guide wire entrance is less than the proximal length of the guide wire that extends out of the guiding catheter.
Just as it sometimes becomes necessary to exchange the device, it also sometimes becomes necessary to exchange the guide wire. A guide wire exchange may be necessary for example when it is determined after the guide wire and the device are in the vessel that the guide wire must be advanced further and a guide wire of a different size or construction or with a different tip "bend" is necessary. With a device with an over-the-wire construction, the guide wire can be withdrawn through the lumen of the device and a second guide wire installed while leaving the device in position. However, with the single-operator-exchange construction, a guide wire exchange cannot readily be performed without withdrawing the device because once the distal end of the first guide wire is withdrawn proximally from the proximal guide wire lumen opening of the device, a second guide wire cannot readily be positioned in the proximal guide wire lumen opening without also withdrawing the device proximally at least so that the proximal guide wire lumen opening is outside the guiding catheter.
Accordingly, it is an object of the present invention to provide a method and device to facilitate a guide wire exchange in conjunction with intravascular devices that incorporate a single-operator-exchange construction.